The complete or partial detachment of ligaments, tendons and/or other soft tissues from their associated bones within the body are relatively commonplace injuries. Tissue detachment may occur as the result of an accident such as a fall, overexertion during a work-related activity, during the course of an athletic event, or in any one of many other situations and/or activities. Such injuries are generally the result of excess stress being placed on the tissues.
In the case of a partial detachment, commonly referred to under the general term “sprain”, the injury frequently heals itself, if given sufficient time and if care is taken not to expose the injury to undue stress during the healing process. If, however, the ligament or tendon is completely detached from its associated bone or bones, or if it is severed as the result of a traumatic injury, partial or permanent disability may result. Fortunately, a number of surgical procedures exist for re-attaching such detached tissues and/or completely replacing severely damaged tissues.
One such procedure involves the re-attachment of the detached tissue using “traditional” attachment devices such as staples, sutures and/or cancellous bone screws. Such traditional attachment devices have also been used to attach tendon or ligament grafts (often formed from autogenous tissue harvested from elsewhere in the body) to the desired bone or bones.
Another procedure is described in U.S. Pat. No. 4,950,270, issued Aug. 21, 1990 to Jerald A. Bowman et al. In this procedure, a damaged anterior cruciate ligament (“ACL”) in a human knee is replaced by first forming bone tunnels through the tibia and femur at the points of normal attachment of the anterior cruciate ligament. Next, a graft ligament, with a bone block on one of its ends, is sized so as to fit within the bone tunnels. Suture is then attached to the bone block, and the suture is thereafter passed through the tibial tunnel and then the femoral tunnel. The bone block is then drawn up through the tibial tunnel and up into the femoral tunnel using the suture. As this is done, the graft ligament extends back out the femoral tunnel, across the interior of the knee joint, and then out through the tibial tunnel. The free end of the graft ligament resides outside the tibia, at the anterior side of the tibia. Next, a bone screw is inserted between the bone block and the wall of femoral bone tunnel so as to securely lock the bone block in position by a tight interference fit. Finally, the free end of the graft ligament is securely attached to the tibia.
In U.S. Pat. No. 5,147,362, issued Sep. 15, 1992 to E. Marlowe Goble, there is disclosed a procedure wherein aligned femoral and tibial tunnels are formed in a human knee. A bone block, with a graft ligament attached thereto, is passed through the tibial and femoral tunnels to a blind end of the femoral tunnel, where the block is fixed in place by an anchor. The graft ligament extends out the tibial tunnel, and the proximal end thereof is attached to the tibial cortex by staples or the like. Alternatively, the proximal end of the ligament may be fixed in the tibial tunnel by an anchor or by an interference screw.
Various types of ligament and/or suture anchors, and anchors for attaching other objects to bone, are also well known in the art. A number of these devices are described in detail in U.S. Pat. Nos. 4,898,156; 4,899,743; 4,968,315; 5,356,413; and 5,372,599.
One known method for anchoring bone blocks in bone tunnels is through “cross-pinning”, in which a pin, screw or rod is driven into the bone, transversely to the bone tunnel, so as to intersect the bone block and thereby “cross-pin” the bone block in the bone tunnel.
In this respect it should be appreciated that the cross-pin (i.e., the aforementioned pin, screw or rod) is generally placed in a pre-drilled transverse passageway. In order to provide for proper cross-pinning of the bone block in the bone tunnel, a drill guide is generally used. The drill guide serves to ensure that the transverse passageway is positioned in the bone so that the transverse passageway intersects the appropriate tunnel section and hence the bone block. Drill guides for use in effecting such transverse drilling are shown in U.S. Pat. Nos. 4,901,711; 4,985,032; 5,152,764; 5,350,380; and 5,431,651.
Other patents in which cross-pinning is discussed include U.S. Pat. Nos. 3,973,277; 5,004,474; 5,067,962; 5,266,075; 5,356,435; 5,376,119; 5,393,302; and 5,397,356.
Cross-pinning methods and apparatus currently exist for fixing a graft ligament in a femoral bone tunnel. However, the femoral cross-pinning methods and apparatus that are presently known in the art do not address the use of a cross-pin in a tibial bone tunnel, which involves a different set of considerations. Among these considerations are anatomical geometries, bone configurations, bone quality, etc.
Accordingly, there exists a need for a method and apparatus for positioning at least one cross-pin so as to fix a graft in a tibial bone tunnel.
There also exists a need for a method and apparatus for positioning at least one cross-pin across a tibial tunnel such that, upon completion of the procedure, the cross-pin is located in the cortical portion of the tibia, adjacent to the tibial plateau.